Generally, cold and hot water dispensers are water supply apparatuses which are installed in houses, offices, restaurants, etc. to conveniently provide cold or hot water to users. Such a cold and hot water dispenser heats water filtered by a filter or water supplied from a mineral water tank so as to provide hot water or cools it to provide cold water.
As shown in FIG. 1, a typical cold and hot water dispenser includes a casing 2, a cold water tank 5 which is disposed in an upper portion of the casing 2, and a hot water tank 7 which is disposed in a medial portion of the casing 2. The cold water tank 5 is a cylindrical tank which is closed on a lower end thereof and is open on an upper end thereof. A cooling coil 6 is wound around an outer circumferential surface of the cold water tank 5. A mineral water tank 1 is placed upside down on an upper surface of the casing 2 in such a way that an opening of the mineral water tank 1 is disposed in the open upper end of the cold water tank 5. The hot water tank 7 is a cylindrical tank which is closed on both upper and lower ends thereof. A heating coil 8 is wound around an outer circumferential surface of the hot water tank 7. A central portion of an upper end of the hot water tank 7 is connected to a central portion of a lower end of the cold water tank 5 by a connection pipe 3. Further, the cold water tank 5 and the hot water tank 7 are respectively connected at lower ends thereof to a cold water valve 51 and a hot water valve 52 by connection pipes 3.
Furthermore, a drain pipe 4 is connected to a lower end of the hot water tank 7. A distal end of the drain pipe is configured such that it is usually closed by a stopper, and when it is required to discharge water from the hot water tank 7, the distal end of the drain pipe 4 opens.
Water that is contained in the hot water tank 7 is heated by the heating coil 8 to a relatively high temperature. Therefore, it is difficult for bacteria to grow in the water in the hot water tank 7. However, because the upper end of the cold water tank 5 is open, cold water in the cold water tank 5 makes contact with the air in the casing 2, thus causing a problem of propagation of bacteria in the cold water. If cold water is stored in the cold water tank 5 for a long period of time, it provides a friendly environment for bacteria.
Furthermore, cold water discharged from the mineral water tank 1 is cooled in the cold water tank 5 by the cooling coil 6 before being supplied into the hot water tank 7 through the connection pipe 3. As such, because mineral water that has been cooled is supplied into and heated in the hot water tank 7, additional power consumption is required.